Search Results (66)

The analysis of time-resolved S₁–S_n absorption spectra in the 0–500 ps range, together with quantum-chemical calculations, uncovered a photorecoordination reaction for the following complexes of CD6 (a bis(aza-18-crown-6)-containing dienone (ketocyanine dye) with a central cyclohexanone fragment): CD6·(Mⁿ⁺)₂ (M = Ba²⁺, Sr²⁺, Ca²⁺, K⁺). This process takes place over hundreds of fs and involves an “axial-to-equatorial” conformational change, with the solvation shell undergoing rearrangement as well. The characteristic photorecoordination times were found to correlate with the stability constants of the complexes. The lifetimes for the fluorescent states of CD6 and its complexes, namely CD6·(Mⁿ⁺)₂ (M = Ba²⁺, Sr²⁺, Ca²⁺, K⁺), are different; ergo, there is no photoejection of crowned cations into the solution. The calculated conformational profiles in the ground and excited states indicate the presence of an energy barrier in this process. A general photorelaxation pathway is suggested for CD6·(Mⁿ⁺)₂ metal complexes (M = Ba²⁺, Sr²⁺, Ca²⁺, K⁺). The coordination of cations via the carbonyl moiety in the dye molecule promotes photorecoordination of metal cations in the cavities of the azacrown ether fragment. Photorecoordination times were found to correlate with the degree of conjugation between the lone pairs in the N atoms of the aza-18-crown-6 ether and the π subsystem in the dye molecules (established for the CD4–CD6 metal–dye complex series, where CD4 and CD5 are related dyes with central cyclobutanone and cyclopentanone fragments, respectively). Full article

A novel two-step strategy was developed for the efficient synthesis of decalin and octahydroindene from lignocellulose-derived platform compounds. In the first step, bicyclic intermediates were directly generated via a cascade dehydration/Robinson annulation of 4-hydroxy-2-butanone with cyclohexanone (or cyclopentanone). Among the evaluated catalysts, CaO demonstrated the highest activity and selectivity. Based on CO₂-TPD results, the excellent performance of CaO can be rationalized by its proper basicity. In the second step, these intermediates were selectively hydrodeoxygenated to decalin (or octahydroindene) over Ni/H-ZSM-5 catalyst. Under the investigated reaction conditions, ~90% overall yields of decalin and octahydroindene were achieved. This work provides a viable strategy for the selective conversion of lignocellulose-derived platform compounds to the additives for improving the thermal stability of aviation fuel. Full article

Furfural is a fascinating bio-based platform molecule that can be converted into useful cyclic compounds, among others. In this work, the hydrogenative rearrangement-dehydration of furfural towards cyclopentanone using a commercially available Pt/C catalyst was investigated in terms of its reaction performance to assess its feasibility as an industrial process. However, acquiring an acceptable cyclopentanone yield proved very difficult, and the reaction was constrained by unforeseen parameters, such as the relative liquid volume in the reactor and the substrate concentration. Most strikingly, the sacrificial formation of furanoic oligomers that precipitated onto the catalyst’s surface was a troublesome key factor that mediated the product’s selectivity versus the carbon mass balance. By applying a biphasic water–toluene solvent system, the yield of cyclopentanone was somewhat improved to a middling 59%, while tentatively positive distributions of reaction components over these solvent phases were observed, which could be advantageous for anticipated down-stream processing. Overall, the sheer difficulty of controlling this one-pot cascade transformation towards a satisfactory product output under rather unfavorable reaction parameters renders it unsuitable for industrial process development, and a multi-step procedure for this chemical transformation might be considered instead. Full article

This study presents colorless polyimides (PIs) suitable for use as plastic substrates in flexible displays, designed to be compatible with controlled soft adhesion and easy delamination (temporary adhesion) processes. For this purpose, we focused on a PI system derived from norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic dianhydride (CpODA) and 2,2′-bis(trifluoromethyl)benzidine (TFMB). This system was selected with the aim of exhibiting excellent optical transparency and low linear coefficient of thermal expansion (CTE) properties. However, fabricating this PI film via the conventional two-step process was challenging because of crack formation. In contrast, modified one-pot polymerization at 200 °C using a combined catalyst resulted in a homogeneous solution of PI with an exceptionally high molecular weight, yielding a flexible cast film. The solubility of PI plays a crucial role in its success. This study delves into the mechanism behind the significant catalytic effect on enhancing molecular weight. The CpODA/TFMB PI cast film simultaneously achieved very high optical transparency, an extremely high glass transition temperature (T_g = 411 °C), a significantly low linear coefficient of thermal expansion (CTE = 16.7 ppm/K), and sufficient film toughness, despite the trade-off between low CTE and high film toughness. The CpODA/TFMB system was modified by copolymerization with minor contents of another cycloaliphatic tetracarboxylic dianhydride, 5,5′-(1,4-phenylene)-exo-bis(hexahydro-4,7-methanoisobenzofuran-cis-exo-1,3-dione) (BzDAxx). This approach was effective in improving the film toughness without sacrificing the low CTE and other target properties. The peel strengths (σ_peel) of laminates comprising surface-modified glass substrates and various colorless PI films were measured to evaluate the compatibility with the temporary adhesion process. Most colorless PI films studied were found to be incompatible. Additionally, no correlation between σ_peel and PI structure was observed, making it challenging to identify the structural factors influencing σ_peel control. Surprisingly, a strong correlation was observed between σ_peel and CTE of the PI films, suggesting that the observed solid–solid lamination is closely linked to the unexpectedly high surface mobility of the PI films. The laminate using CpODA(90);BzDAxx(10)/TFMB copolymer exhibited suitable adhesion strength for the temporary adhesion process, while meeting other target properties. The modified one-pot polymerization method significantly contributed to the development of colorless PIs suitable for plastic substrates. Full article

Due to the widespread utilization of biodegradable plastics (such as polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT)) as alternatives to traditional plastics such as PE and PP, the disposal of the end-of-use biodegradable plastic products mixed with other waste has increasingly become an issue. This study investigated the co-pyrolysis characteristics, kinetic features, product formation, and synergistic effects of common biodegradable plastics (PLA and PBAT) and kitchen waste (KW) at different mass ratios, using TGA-FTIR-GC/MS. The findings revealed that the addition of KW significantly lowered the pyrolysis temperature. For the PLA and KW with a 2:1 mass ratio, the activation energy decreased by approximately 35 kJ/mol compared to PLA pyrolysis alone. The production of lactide increases significantly, while the formation of aldehydes and CO decreases. Moreover, the co-pyrolysis of KW and PBAT reduces the formation of harmful substances such as tetrahydrofuran and cyclopentanone. This study provides valuable insights into the pyrolysis process of mixed biodegradable plastic waste, offering a better approach for the disposal of similar forms of waste and resource recovery scenarios. Full article

Leukemia, one of the major causes of cancer death, ranks 11th worldwide among cancer-related deaths. The current treatment of leukemia faces challenges recently due to a high burden of side effects. It is well established that curcumin has anticancer and tumor-suppressing activities in several cancers in addition to leukemia. Accordingly, 15 derivatives were designed and prepared to improve the shortcomings of curcumin, such as poor aqueous solubility, chemical instability, and low bioavailability. All 15 were evaluated for cytotoxicity against the leukemic cell line MOLT-4, which led to the prioritization and further evaluation of compound curcuminoid (2E,5E)-2,5-bis((3-(4-nitrophenyl)-1-phenyl-1H-pyrazol-4-yl)methylene)cyclopentan-1-one 5i. 5i. Compared to curcumin, 5i was significantly more effective in inducing mitochondrial dysfunction in MOLT-4 cells; hence increased ROS production and cytotoxicity. Treatment groups showed change in mitochondrial membrane potential by flow cytometry analysis. Moreover, tumor volume reduction observed with 5i treatment in Dalton’s Lymphoma model was accompanied with low toxicity. Intrinsic pathways of apoptosis was initiated by compound 5i that lowered Bcl-2 expression while augmenting cytochrome c, Bak and Bax levels both in vivo and in vitro. These results showcase the potent antiproliferative as well as cytotoxic effects of 5i at nanomolar doses against leukemia being at least 60 times more effective than curcumin. Full article

A rapid synthesis of structurally novel s-indacene-1,5-dione and cyclopentanone-fused isoxazole derivatives in generally moderate yields was achieved through the NaNO₂-catalyzed/involved transformation of cyclopentenone-MBH acetates. Under similar reaction conditions, two different reaction pathways were observed depending on the type of aryl substituent on MBH acetates. In the formation of s-indacene-1,5-diones, NaNO₂ is proposed to act as a nucleophilic catalyst to initiate the stepwise dimeric cyclization/oxidative aromatization, whereas in the formation of isoxazole derivatives, it plays the role of nucleophilic reagent of (3+2) cycloaddition. Using NaNO₂ as an inexpensive and readily available catalyst or reaction component, mild reaction conditions, operational simplicity, and metal-free transition are the main advantages of this work. Full article

Two natural ent-kaurene diterpenoids, ent-15α-angeloyloxykaur-16-en-3β-ol (7) and ent-15α-angeloyloxykaur-16-en-3β,9-diol (8), were extracted from the aerial parts of Distichoselinum tenuifolium, and six new derivatives were synthesised from compound (7). The antitumour properties of these natural and derivative ent-kaurenes (2, 7, 9–13) were evaluated in three cancer cell lines: HT29 (colon cancer), HepG2 (hepatocellular carcinoma), and B16-F10 (murine melanoma). Among them, the synthesised ent-kaurene (13) containing an exomethylene–cyclopentanone moiety showed the strongest antiproliferative effects in all cell lines tested, with significantly lower IC₅₀ values around 2.5 μM. Compounds 13 and 12, together with their precursor (7), were selected for further comparative cytometric and microscopic analyses. Cell cycle studies revealed that derivatives 12 and 13 exhibited promising cytostatic activity by inducing selective G2/M phase arrest, particularly effective in HT29 and HepG2 cells. Conversely, precursor (7) showed no significant effect on B16-F10 cell cycle distribution. The Annexin V-FITC/PI double staining assay confirmed the robust apoptotic effects of compounds (7), 12 and 13, with compound 13 inducing up to 99% total apoptosis and exhibiting significant apoptotic activity in all cell lines tested. These apoptotic effects were closely linked to mitochondrial dysfunction, as evidenced by a marked loss of mitochondrial membrane potential and reduced Rh123 fluorescence in treated cells, thereby activating the intrinsic apoptotic pathway. These findings highlight the critical role of mitochondrial disruption in the cytotoxic mechanisms of these ent-kaurenes and underscore their potential as promising anticancer agents. Full article

The cocrystallization of 1,3,5,7-tetranitro-1,3,5,7-tetrazolidine (HMX) with cyclopentanone was achieved via a controlled cooling method, followed by comprehensive characterization that confirmed the α-configuration of HMX within the cocrystal. The enthalpy of dissolution of HMX in cyclopentanone was assessed across a range of temperatures using a C-80 Calvert microcalorimeter, revealing an endothermic dissolution process. Subsequently, the molar enthalpy of dissolution was determined, and kinetic equations describing the dissolution rate were derived for temperatures of 303.15, 308.15, 313.15, 318.15, and 323.15 K as follows: dα⁄dt = 10^−2.46(1 − α)^0.35, dα⁄dt = 10^−2.19(1 − α)^0.79, dα⁄dt = 10^−1.76(1 − α)^1.32, dα⁄dt = 10^−1.86(1 − α)^0.46, and dα⁄dt = 10^−2.02(1 − α)^0.70, respectively. Additionally, molecular dynamics (MD) simulations investigated the intermolecular interactions of the HMX/cyclopentanone cocrystallization process, demonstrating a transformation of HMX from β- to α-conformation within the cyclopentanone environment. Theoretical calculations performed at the ωB97XD/6-311G(d,p) level affirmed that α-HMX exhibited stronger binding affinity toward cyclopentanone compared to β-HMX, corroborating experimental findings. A comprehensive understanding of the dissolution behavior of HMX in cyclopentanone holds significant implications for crystal growth methodologies and cocrystallization processes. Such insights are pivotal for optimizing HMX dissolution processes and offer valuable perspectives for developing and designing advanced energetic materials. Full article

An overview of solvent replacement strategies shows that there is great progress in green chemistry for replacing hazardous di-polar aprotic solvents, such as N,N-dimethylformamide (DMF), 1-methyl-2-pyrrolidinone (NMP), and 1,4-dioxane (DI), used in processing active industrial ingredients (APIs). In synthetic chemistry, alcohols, carbonates, ethers, eucalyptol, glycols, furans, ketones, cycloalkanones, lactones, pyrrolidinone or solvent mixtures, 2-methyl tetrahydrofuran in methanol, HCl in cyclopentyl methyl ether, or trifluoroacetic acid in propylene carbonate or surfactant water (no organic solvents) are suggested replacement solvents. For the replacement of dichloromethane (DCM) used in chromatography, ethyl acetate ethanol or 2-propanol in heptanes, with or without acetic acid or ammonium hydroxide additives, are suggested, along with methanol acetic acid in ethyl acetate or methyl tert-butyl ether, ethyl acetate in ethanol in cyclohexane, CO₂-ethyl acetate, CO₂-methanol, CO₂-acetone, and CO₂-isopropanol. Supercritical CO₂ (scCO₂) can be used to replace many organic solvents used in processing materials from natural sources. Vegetable, drupe, legume, and seed oils used as co-extractants (mixed with substrate before extraction) can be used to replace the typical organic co-solvents (ethanol, acetone) used in scCO₂ extraction. Mixed solvents consisting of a hydrogen bond donor (HBD) solvent and a hydrogen bond acceptor (HBA) are not addressed in GSK or CHEM21 solvent replacement guides. Published data for 100 water-soluble and water-insoluble APIs in mono-solvents show polarity ranges appropriate for the processing of APIs with mixed solvents. When water is used, possible HBA candidate solvents are acetone, acetic acid, acetonitrile, ethanol, methanol, 2-methyl tetrahydrofuran, 2,2,5,5-tetramethyloxolane, dimethylisosorbide, Cyrene, Cygnet 0.0, or diformylxylose. When alcohol is used, possible HBA candidates are cyclopentanone, esters, lactone, eucalytol, MeSesamol, or diformylxylose. HBA—HBA mixed solvents, such as Cyrene—Cygnet 0.0, could provide interesting new combinations. Solubility parameters, Reichardt polarity, Kamlet—Taft parameters, and linear solvation energy relationships provide practical ways for identifying mixed solvents applicable to API systems. Full article

The synthesis of dimethyl adipate (DAP), a stable configuration of adipic acid, from biomass-derived cyclopentanone (CPO) and dimethyl carbonate (DMC) constitutes an attractive greener route than petroleum-based industrial processes. Solid basic catalysts such as MgO, Mg₅(CO₃)₄(OH)₂·4H₂O, KOCH₃ and Ca(OCH₃)₂ have been used achieving a DAP yield up to 30% at 533 K. In addition to the type of catalyst, other operating conditions such as the substrate, reaction time, temperature and CPO concentration have been studied. The methylation of DAP and CPO and the self-aldol condensation of CPO to form dimers and oligomers are reactions that occur in parallel with the production of DAP. It has been established that the main challenge is the self-aldol condensation of CPO. It has been identified that at short reaction times, to prevent methylation, and at dilute concentrations, to avoid CPO self-condensation, the DAP formation rate is much higher than these other competitive reactions. Finally, it should be noted that a DAP productivity up to 3.45 g·gcat⁻¹·h⁻¹ has been achieved under mild conditions. Full article

Layered double oxides are widely employed in catalyzing the aldol condensation for producing biofuels, but its selectivity and stability need to be further improved. Herein, a novel MCM-41-supported Mg–Al-layered double oxide (LDO/MCM-41) was prepared via the in situ integration of a sol–gel process and coprecipitation, followed by calcination. This composite was first employed to catalyze the self-condensation of cyclopentanone for producing high-density cycloalkane precursors. LDO/MCM-41 possessed large specific surface area, uniform pore size distribution, abundant medium basic sites and Bronsted acid sites. Compared with the bulk LDO, LDO/MCM-41 exhibited a higher selectivity for C10 and C15 oxygenates at 150 °C (93.4% vs. 84.6%). The selectivity for C15 was especially enhanced on LDO/MCM-41, which was three times greater than that on LDO. The stability test showed that naked LDO with stronger basic strength had a rapid initial activity, while it suffered an obvious deactivation due to its poor carbon balance. LDO/MCM-41 with lower basic strength had an enhanced stability even with a lower initial activity. Under the optimum conditions (50% LDO loading, 170 °C, 7 h), the cyclopentanone conversion on LDO/MCM-41 reached 77.8%, with a 60% yield of C10 and 15.2% yield of C15. Full article

The triple condensation of cyclopentanone or indanone to trindane (C₁₅H₁₈) or truxene (C₂₇H₁₈), respectively, provides convenient access to molecular skeletons on which major fragments of the prototypical fullerene C₆₀ can be assembled. In particular, early approaches (both organic and organometallic) towards sumanene, as well as the final successful synthesis, are described. Organometallic derivatives of trindane have been prepared in which Cr(CO)₃, Mo(CO)₃, [Mn(CO)₃]⁺ or [(C₅H₅)Fe(CO)₂]⁺ are η⁶-bonded to the central arene ring. The debromination of hexabromotrindane yields trindene, which forms a tri-anion to which as many as three organometallic fragments, such as Mn(CO)₃, W(CO)₃Me, or Rh(CO)₂, may be attached. Truxene forms complexes whereby three metal fragments can bind either to the peripheral arene rings, or to the five-membered rings, and these can be interconverted via η⁶ ↔ η⁵ haptotropic shifts. Truxene also forms a double-decker sandwich with Ag(I) bridges, and decacyclene, C₃₆H₁₈, forms triple-decker sandwiches bearing multiple cyclopentadienyl-nickel or -iron moieties. The organic chemistry of trindane has been investigated, especially with respect to its unexpectedly complex oxidation products, which were only identified unambiguously via X-ray crystallography. The three-fold symmetric trindane framework has also been used as a template upon which a potential artificial receptor has been constructed. Finally, the use of truxene and truxenone derivatives in a wide range of applications is highlighted. Full article

In this paper, fluorinated compounds based on sulfolane, cyclopentanone, and gamma-butyrolactone are studied computationally, focusing on their applicability in electrochemical devices and acid–base-related studies. Candidates for solvents with (1) high polarity, (2) good electrochemical stability, and (3) low basicity were searched for. Some of the compounds are studied here for the first time. Electrochemical stabilities, dielectric constants, boiling points, basicities, and lipophilicities were estimated using DFT and COSMO-RS methods with empirical corrections. The effect of fluorination on these properties as well as the bond parameters was studied. The possible synthesis routes of the proposed compounds are outlined. Some molecules display a combination of estimated properties favorable for a solvent, although none of the studied compounds are expected to surpass acetonitrile and propylene carbonate by the width of the electrochemical stability window. Full article

The cross-conjugated dienones containing the 1,5-diaryl-3-oxo-1,4-pentadienyl pharmacophore have diverse biological activities. These sometimes-called monocarbonyl analogs of curcumin (MACs) have especially pronounced biological activity when containing an electron-withdrawing group at the ortho-position of the benzene ring. Their biological activity most likely stems from a selective Michael reaction with thiols. It has been reported in the literature that certain MACs (in particular, EF24) react as electrophiles with glutathione and form bis adducts in vitro. Five MACs were prepared ((2E,5E)-2,5-bis(2-bromobenzylidene)cyclopentanone, (2BrCP), (2E,6E)-2,6-bis(2-bromobenzylidene)cyclohexanone (2BrCX, B2BrBC), (2E,6E)-2,6-bis(2-bromobenzylidene)- 4-tert-butyl-cyclohexanone (4tB2BrCX), (3E,5E)-3,5-bis(2-bromobenzylidene)-4-piperidone, (2Br4PIP) and (3E,5E)-3,5-bis(2-fluorobenzylidene)-4-piperidone, EF24), purified and characterized by spectroscopic means. The relative reactivity of these MACs towards 2-(dimethylamino)ethanethiol was assessed via a previously developed UV-Vis spectroscopic method and compared to EF24, which reacts readily in solution with thiols such as glutathione and cysteamine. All of the bis(2-bromobenzylidene) MACs react slower with 2-(dimethylamino)ethanethiol in 80:20 (v/v) acetonitrile/water compared to EF24. The relative reactivity of the analogs with 2-(dimethylamino)ethanethiol followed the order EF24 > 2Br4PIP > 2BrCX > 2BrCP > 4tB2BrCX. Full article